Two months after a top executive of Philip Morris Cos. testified in 1994 before Congress that the cigarette maker did not "manipulate or independently control" nicotine in its products, company scientists reported on experiments that indicated that they could produce "enhanced" nicotine effects on a smoker's nervous system, an internal company document shows.

The June 1994 research report also found that altering the nicotine's chemical form likely "increased the rapidity" at which nicotine, the addictive substance in cigarettes, entered a smoker's bloodstream, the document shows.

The document does not indicate whether the research was used in commercial products.

All the major tobacco producers, including Philip Morris, have repeatedly denied that they manipulate or control nicotine levels or design their cigarettes to deliver specific levels of the chemical. But thousands of internal memorandums released on Friday by the companies provide a portrait of an industry obsessed with nicotine, its physiological and pharmacological effects and the myriad ways in which it might be controlled and altered while being delivered to the smoker.

Over the past three decades, the tobacco industry poured millions of dollars and thousands of research hours into exploring how to "manipulate," "control" and "augment" nicotine, the documents show. The methods explored included treating nicotine with ammonia, adding other chemicals, new filter and cigarette paper designs, and direct addition of nicotine, according to the documents.

The documents were initially collected by lawyers for Minnesota for use in a lawsuit against the nation's four largest cigarette companies: Philip Morris; RJ Reynolds Tobacco Co., a subsidiary of RJR Nabisco Holding Corp.; Lorillard Tobacco Co., a subsidiary of Loews Corp.; and Brown & Williamson Tobacco, a subsidiary of BAT Industries.

The cigarette makers had initially resisted disclosing the records. But last month, after the Minnesota case began, they agreed to publicly disclose some of the records from the case in an apparent bid to improve prospects for congressional passage of the $368.5 billion tobacco settlement proposal reached in June between the industry and 40 state attorneys general.

The documents posted on Friday on the Internet by the companies represent the first installment of those records. The companies are continuing to fight disclosure of 39,000 other documents involving evidence of possible fraud or other crimes by cigarette company officials and their lawyers.

In the 1994 Philip Morris study, subjects were given cigarettes containing tobacco additives that varied the cigarette smoke's pH, the measure of its acidity or alkalinity.

The study found that as the smoke pH increased in alkalinity, nicotine entered the bloodstream more rapidly. The study also found that cigarettes containing more alkaline substances produced "enhanced electrophysiological and subjective responses."

Earlier industry studies found that while the use of chemicals such as ammonia or other alkaline compounds did not affect overall nicotine delivery, they did produce a chemical reaction that converted nicotine from its bound, or less physiologically active, form, to its free form.

The higher proportions of free nicotine produced greater "physiological satisfaction," "kick" or "impact" on a smoker, various documents show.